| $$ \begin{aligned}\frac{x^3-x^2-5x-3}{x^2+2x+1}& \xlongequal{ \color{blue}{ \text{\normalsize{ \htmlClass{explanationCircle explanationCircle1}{\textcircled {1}} } }}}x-3\end{aligned} $$ | |
| ① | Simplify $ \dfrac{x^3-x^2-5x-3}{x^2+2x+1} $ to $ x-3$. Factor both the denominator and the numerator, then cancel the common factor. $\color{blue}{x^2+2x+1}$. $$ \begin{aligned} \frac{x^3-x^2-5x-3}{x^2+2x+1} & =\frac{ \left( x-3 \right) \cdot \color{blue}{ \left( x^2+2x+1 \right) }}{ 1 \cdot \color{blue}{ \left( x^2+2x+1 \right) }} = \\[1ex] &= \frac{x-3}{1} =x-3 \end{aligned} $$ |